Another type of observables that are sensitive to \({\cal CP}\) -violating interactions are electric dipole moment (EDM) measurements. These were used in Ref. [1]} to set upper bounds on the \({\cal CP}\) -odd Higgs–top-quark coupling of \({\cal O}(0.5)\) . The most recent EDM measurements (see e.g. Refs. [2]}, [3]}) which were not taken into account in Ref. [1]} may lead to stronger constraints (see Refs. [5]}, [6]}, [7]}, in which the complementarity between collider and BAU constraints is also discussed). In the analysis of these constraints, however, it is assumed that the Higgs couples only to third-generation fermions. While assuming SM values also for the first- and second-generation fermions leads to substantially stricter bounds, non-zero \({\cal CP}\) -odd components in the couplings of the Higgs boson to leptons or first- and second-generation quarks, which are hardly experimentally accessible so far, could actually loosen the constraints on the \({\cal CP}\) -odd component of the top-Yukawa interaction (see Refs. [8]}, [9]}, [10]}).
